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[noun] The emergence of life forms emerging from non-living chemical systems. In contrast with spontaneous generation, abiogenesis is not a process that biologists think continues in a particular environment, such as a planet or moon, once a living system has emerged.

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[noun] In science, an abstract is a brief statement of essential information contained within a document or presentation. An abstract is not an introduction, rather it concentrates the most pertinent information to facilitate understanding of the main points of the document. Most scientific journal articles include an abstract at the beginning of the article which is uploaded to literature databases to facilitate information searches; and scientists also submit abstracts that summarize what they will present at a scientific meeting. See this Writing@CSU page for additional information.

[noun] The change in an object's velocity over time, measured in distance per unit time per unit time (for example meters per second per second or m/s2). Compare to velocity. Acceleration (a) is calculated by dividing the change (symbolized by Δ, the Greek letter delta) in velocity (v) by the change in time (t):

a = Δv/ Δt.

This can also be written as:

a = v2-v1/ t2-t1, where v1 and t1 denote the starting velocity and time and v2 and t2 denote the ending velocity and time.

To illustrate, imagine a car speeding up (accelerating) from a stand still (0 meters/second) to a speed of 15 meters/seconds over the course of 5 seconds. The car's total increase in velocity is 15 meters/second. During each of the 5 seconds that the car is accelerating, its velocity increases by 3 meters/second until it reaches its top speed. (After one second the car is traveling at a velocity of 3 meters/second; after 2 seconds, it's traveling at a velocity of 6 meters/second, and so on). Therefore, the car's rate of acceleration is 3 meters per second per second or 3 m/s2. Using the equation above:

a = v2-v1/ t2-t1
a = 15-0 / 5-0
a = 15/5
a = 3 m/s2

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[noun] In science, the term accuracy describes how well a measurement approximates the theoretically correct value of that measurement, for example, how close an arrow strikes to the center of a target. Accuracy provides a measure of the systematic error associated with a value. Compare to precision. See the module Uncertainty, Error, and Confidence.

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[noun] Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different scientists (listed in parentheses). 1) (Arrhenius) a compound that releases hydrogen ions (H+) in solution; 2) (Brønsted-Lowry) a compound capable of donating hydrogen ions, 3) (Lewis) a compound that can accept a pair of electrons from a base.

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[noun] The energy required to initiate a chemical reaction or process, abbreviated Ea. For example, a cigarette lighter requires activation energy (provided in the form of a spark) to initiate the reaction of fuel with oxygen.

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[noun] The opposite of passive transport, active transport involves the input of energy (usually in the form of ATP), the building of concentration gradients, and the action of a membrane pump to create high concentrations of molecules.

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[person] Welsh astronomer, born near Launceston, Cornwall (1819-1892). He successfully predicted the existence of a then-unknown planet (Neptune) based on perturbations in Uranus' orbit. He also studied the Leonid meteor shower, successfully predicting its occurrence and proving its association with Tempel's Comet.

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[noun] The interaction of a molecule with something other than itself, often related to mechanical or electrostatic forces. For example, water forms a meniscus within a glass cylinder due to adhesive forces between the water and glass.

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[person] (1807-1873) A geologist and paleontologist, born and educated in Europe, but regarded as one of the founding fathers of American science. While in Switzerland and France, Agassiz studied comparative anatomy under Georges Cuvier in 1832, focusing on fossil and modern fish. In 1836, he began to study glacial landforms and became a strong proponent of the theory of glacial ice ages. In 1848, Agassiz accepted a position at Harvard University and moved to the United States, where he helped found the National Academy of Sciences, the American Association for the Advancement of Science, and served as a regent of the Smithsonian Institution.

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[noun] (15th-early 17th century) also referred to as the Age of Discovery, this was a time in history during which Europeans explored and mapped the world, establishing primary contacts with Africa, the Americas, Asia and Oceania. In particular, Portuguese and Spanish explorers made ocean voyages in search of alternative trade routes to the Indies, the source of gold, silver and spices.

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[noun] The clumping together cells bearing antigens, microorganisms, or particles when in the presence of an antibody. When the clumping involves red blood cells, the process is called hemagglutination.

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[person] (aka Georg Pawer/Bauer) German geologist and medical doctor, born in Glauchau, Saxony (1494-1555). Agricola wrote several influential geological manuscripts, including De Natura Fossilium (1546), De Ortu et Causis Subterraneorum (1546) and De Re Metallica (published posthumously in 1556). The later is his most influential work, being a compendium of everything then known about mining, including (but not limited to) equipment, methods of surveying for and extracting minerals, mine administration, and the occupational diseases of miners.

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[noun] A scientist whose focus is the management of soil and the production of crops. Agronomy includes the study of farming practices: The effect a farmer’s actions have on the soil and surrounding environment.

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[person] The Latinized name for the Muslim scientist Abū-Alī al-Hasan ibn al-Hasan ibn al-Haytham who was born in Basra, Mesopotamia (Iraq) (965-1039 CE). Alhazen made significant contributions in the fields of astronomy, mathematics, medicine, and most significantly, optics. His work in optics irrefutably proved that vision is a function of external light rays entering the human eye; and his rigorous and quantitative approach formed the basis of the modern experimental method in science.

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[noun] In statistical testing, an alternative hypothesis (H1) is a statement describing the possibility that an observed result or effect is genuine. The alternative hypothesis is always compared to a null hypothesis (H0), and H1 is not accepted until statistical testing shows that it should be accepted in favor of H0. For example, in an evaluation of data regarding the pain relieving properties of a new drug, the alternative hypothesis would state that the new drug has an effect on pain relief compared to a control. Accepting H1 does not indicate that the observed result or effect is large or important, simply that it is favored in terms of probability of the outcome.

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[organization] A professional society established in 1848 that serves scientists in all disciplines. The mission of AAAS is to "advance science, engineering, and innovation throughout the world for the benefit of all people." AAAS hosts an annual meeting, publishes the journal Science, and has numerous programs that promote science education and the interactions between science and policy. More information about AAAS can be found on their website.

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[organization] A professional society for chemists established in 1876. The mission of ACS is "to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and its people." In addition to publishing journals and holding meetings, ACS provides competitive funding for research through its Petroleum Research Fund. More information about ACS can be found on their website.

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[organization] A professional society established in 1919, originally as part of the National Academy of Sciences, but now an independent organization. The mission of AGU is "to promote discovery in Earth and space science for the benefit of humanity"; the primary means of achieving that mission is through hosting two annual meetings and publishing numerous journals. More information about AGU can be found on their website.

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[noun] Biochemical molecules that contain at least one amine group (-NH2) and at least one carboxylic acid group (-COOH) and conform to the general formula NH2-R-COOH, where R is an organic molecule. Amino acids are essential basic building blocks of proteins.

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[adjective] Having no specific arrangement or organization. Amorphous solids are those that have no specific arrangement of atoms and usually melt over a broad temperature range and break unpredictably, producing fragments with irregular, often curved surfaces.

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[person] French mathematician born in Poleymieux, Lyon (1775-1836). Ampere researched metaphysics, physics, and chemistry, but he focused on mathematics, which he taught at the Ecole Polytechnique in Paris. His key contributions to science include his work on partial differential equations, the discovery of fluorine, and studies on the wave theory of light. His most important work was the Memoir on the Mathematical Theory of Electrodynamic Phenomena, Uniquely Deduced from Experience, in which he described a mathematical derivation for the electrodynamic force law. The Amp (a measurement of electrical current) is named in his honor.

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[person] (610–546 BCE) Ionian Greek philosopher. He put forth an early idea about human origins in which humans had evolved gradually from fish. This echoes aspects of modern evolutionary theory. However, in ancient Greece Anaximander’s idea developed into the concept of spontaneous generation that grew into a complex hypothesis that persisted for 24 centuries.

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[noun] A convergent plate boundary, where oceanic crust is being subducted beneath continental crust. Named after the Andes Mountains in South America, which are the classic example of a continent-ocean convergence.

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[noun] An extrusive igneous rock of intermediate composition, often gray in color. The main minerals present in andesite are plagioclase and hornblende. The word "andesite" comes from the Andes Mountains in South America, where this rock type is common. Around the world, andesitic magma erupts out of volcanoes along convergent boundaries, and its intrusive equivalent is diorite.

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[noun] The momentum possessed by an object in rotation around a point, it is the analog to linear momentum. In physics, one of the fundamental conserved quantities in classical and quantum mechanics (the others are mass, energy, and linear momentum). Total angular momentum of a particle in quantum mechanics is the sum of the spin angular momentum and the orbital angular momentum. The units of Planck's constant are units of angular momentum.

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[noun] A deviation from the normal or expected, sometimes expressed with respect to an average value. Anomalies are described in many kinds of data, and are features of datasets that require explanation.

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[acronym] A statistical test of significance for three or more subsamples. Short for “analysis of variance,” ANOVA is a method of statistical hypothesis testing that generalizes Student’s t-test to more than two groups without incorporating the additional error associated with repeatedly conducting tests of statistical significance.

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[noun] A Y-shaped protein molecule that is produced by the immune system in response to infection by an antigen. Different antigens provoke the production of different antibodies. Antibodies fight disease by attaching themselves to antigens, destroying them or surrounding them so that they cannot attack the body.

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[noun] (Also known as top-level predator or alpha predator) A carnivorous species at the top of the food chain in a particular ecosystem with no natural predators other than humans. Examples include large cats (lions, jaguars, tigers, etc.), sharks, wolves, bears, anaconda snakes, and others. Removing these top predators can have ripple effects throughout an ecosystem.

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[noun] (plural of archaeon) One of three domains of life on Earth (the other two being Bacteria and Eukaryota), consisting of single-celled organisms that are prokaryotes (lacking membrane-bound organelles), yet phylogenetically and biochemically are as distinct from the Bacterial domain as they are from Eukaryotes.

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[person] Greek mathematician, born in Syracuse, Sicily (287-212 BCE). Little is known about Archimedes' life, but he is best known for devising the water displacement method of measuring the volume of an irregularly-shaped object (which he possibly conceived of while getting into his bathtub). He is also credited with developing the foundations of integral calculus and mathematical physics.

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[person] A Greek philosopher born in Stagira (384-322 BCE). He joined Plato's Academy in Athens (then being run by Eudoxus) at the age of 17. After attending the academy, he taught there for 20 years before founding his own school, the Lyceum. He is remembered primarily for his works on deductive logic and the use of philosophical reasoning to address questions about the natural world.

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[person] Swedish physical chemist born in Vik (1859-1927). Arrhenius is most famous for what is now known as the Arrhenius equation, which relates the rate of chemical reactions to temperature and activation energy. Arrhenius was awarded the Royal Society's Davy medal and the Faraday medal of the Chemical Society in 1914, and the Nobel Prize for Chemistry in 1903 based on his early work on the conductivity of electrolytes in solution.

[noun] The semi-molten layer of the earth which starts at ~70-200 km depth and ends at 660 km depth. The asthenosphere is part of the mantle, and is composed primarily of the rock peridotite. The asthenosphere can flow very slowly, allowing rigid pieces of the lithosphere to move around on top of it.

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[noun] Compare with Bohr radius and hartree. A system of non-SI units used in quantum chemistry to simplify calculations and mathematical expressions. The definitions of atomic units include physical constants (like the speed of light, the rest mass of the electron, and other quantities that never change), so that all constants drop out of expressions when atomic units are used.

[noun] As listed on the periodic table, the atomic weight is a weighted average of the masses of stable isotopes of an element that occur in nature. Given in grams, the atomic weight is the weight of one mole of atoms of an element. Atomic weight is often used interchangeably with atomic mass.

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[noun] The behavior of waves as they radiate out from a source. As distance from the source increases, intensity of the waves decreases. Attenuation occurs because the same amount of energy is being spread out over a larger area.

[person] (October 21, 1877 - February 2, 1955) A Canadian-born American physician and medical researcher, considered one of the founders of immunochemistry, a branch of chemistry that deals with the immune system. Avery was part of the team, along with Maclyn McCarty and Colin MacLeod, which discovered that DNA is the genetic basis of life. Later, Avery served as president of the American Association of Immunologists, the American Association of Pathologists and Bacteriologists, and the Society of American Bacteriologists, and received numerous honors and recognitions for his medical research.

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[noun] The relationship between a gas’s volume (V) and amount (n, in moles), which was based on the work of the Italian scientist Amedeo Avogadro. Avogadro’s Law states that at a constant pressure and temperature, a gas’s volume is directly proportional to its amount.

[person] Italian chemist and mathematician born in Turin (1776-1856). Avogadro was schooled to be an ecclesiastical lawyer, but retained an interest in natural philosophy, and studied mathematics and physics on his own. In 1811, Avogadro made the first distinction between molecules and atoms. He further suggested Avogadro’s Law: Equal volumes of gas at the same pressure and temperature contain the same number of molecules. Avogadro's number, which defines the number of atoms in a mole, is named after him for his disambiguation of molecules.